Carbide Shield Cutter
UKOcarbide manufacture the Tungsten Carbide Tips for Shield Cutter in various sizes, Tungsten Carbide Grades as well as surface conditions. All the Carbide Shield Cutter Tips must be inspected strictly with the ultrasonic, if everything is qualified that will be shipped out. High density, abrasion resistance, and impact resistance guarantee a long service life.
Tunnel borer carbide tips are widely used in petroleum, natural gas, coal, road construction and other types of mining exploration,mining excavation & processing areas in which tools are mainly as petroleum drill bits, coal cutting bits, milling planer bits,geologic tools, compound drill bits and their completed tools.
Tunnel borer carbide tips are very advanced underground tunnel construction equipment, it does not affect the ground condition under the conditions of operation, thus greatly improve the feasibility of the construction and reduce the cost.
Shield machine of Tunnelling tool is a kind of advanced equipment for underground tunnel construction. This equipment can do the field operation that not affect any construction on the ground. This is the available and the best choice for crowd city areas, protecting buildings or historic sites on the ground.
There has a very big circle blade in the front of the shield machine. And various kinds of cutters are mounted on the blade. In order to promote a stable and long lifetime of the application, we have research and developed special tungsten carbide materials that mainly suitable for tunnel borer machine: high impact toughness, high abrasion resistance, stable physical ability, the appearance of fine workmanship, etc.
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What is a carbide shield cutter head?
"The shield machine is a tunnel boring machine using the shield method. The shield construction method is that the tunnel machine builds (lays) the" shield "(referring to the supporting segment) of the tunnel at the same time as the tunnel. Construction method. Internationally, the generalized shield machine can also be used in rock formations, but it is different from the open (non-shield method) tunnel boring machine.
In China, the tunnel boring machine used for the soft ground is called (narrow sense) shield machine, and the rock tunnel is called (narrow sense) TBM. Shield machines are generally divided into hand-shielded shields, squeeze shields, semi-mechanical shields (local pressure, global pressure), mechanical shields (open chest cutting shields, pneumatic shields) according to the working principle. , Mud pressurized shield, earth pressure balanced shield, hybrid shield, special shield). "
Carbide shield cutter head is a key component of shield machine construction to achieve rock breaking. It is characterized by the high price, long supply cycle, large consumption and frequent replacement. And the service life of the cutter directly affects the cost and schedule of shield construction.
Major countries (USA, Germany, and Japan) that produce shield machines abroad have professional rock Carbide Shield Cutter Tips manufacturers. They have conducted long-term research on cutting tools, and constantly improve and update rock cutting tools to make their products competitive. For example, the diameter of the hob is increased from 12 inches to 19 inches. Today's tools are specially designed and manufactured according to specific conditions.
The domestic research of shield hobs for shield machines started in the 1960s. After nearly 30 years of development, until the mid-1990s, small-diameter hobs with a diameter of less than 400 mm were mainly used in practice. Due to the domestic demand for shield tunneling machine tools and the improvement of China's overall industrial technology level, the research of rock breaking tools has developed significantly in China and is gradually replacing imported tools.
What does a shield machine cutter head do?
(1) Type and cutting principle of the tools
At present, shield machine tools are divided according to cutting principles. Generally, there are two types of hobs and cutters (these two types of tools can be further subdivided according to the different properties of the tunnel surrounding rock and the cutting purpose). The cutting principle of the hob is mainly that the tool relies on crushing rock to break the rock, which is generally used for rock tunneling. A hob cutter can also be used when gravel (larger than 400mm in diameter) has a large particle size although it passes through a loose stratum, and the content reaches a certain proportion.
In addition, in the case where the tunnel's geological conditions are complex and changeable, and the rock (not too high in strength) staggers frequently with the general soil (or clay or sandy soil), it is also possible to use a hob cutter, that is, in a composite shield machine use.
The cutting principle of the cutter is mainly that while the shield machine is advancing forward, the cutter generates a shear force and a radial direction (the direction of the cutter's rotation) to the soil of the excavation surface with the cutter's rotation. Cutting force continuously cuts down the soil in front of the excavation surface. The cutter is generally suitable for loose bodies such as sand pebble, sand, clay, etc. with a particle size of less than 400mm.
(2) Shape and function of the main shield cutter head
The cutter is the main tool for cutting the excavated surface soil. The general shape of the cutter is shown in Figure 15. In general, the values of β (front angle) and α (back angle) vary with the characteristics of the cutting formation. The value ranges from 5 ° to 20 °. Clay formations are slightly larger and sandy pebble formations are smaller. For example, the stratigraphic characteristics of Beijing, β (front angle) and α (back angle) values are recommended to be 15 °.
② Leading knife (also called leading knife)
As its name implies, a lead knife is a tool that cuts soil in advance. The leading tool is mainly designed to work with the combination of cutting tools in the design. When the cutter cuts the soil, the cutting tool cuts the soil before the cutter cuts the soil, and cuts the soil into pieces, creating good cutting conditions for the cutter. According to its function and purpose, the lead section is generally smaller than the cutting section. The use of advanced cutters can generally significantly increase the fluidity of the cutting soil, greatly reduce the torque of the cutter, improve the cutting efficiency of the cutter, and reduce the wear of the cutter. The effect is very obvious in loose formations, especially sand and pebble formations.
③ Coiled Shell Knife
The coiled shell knife is essentially a leading knife. When the shield machine passes through the sand and pebble stratum, especially when it is a large particle sand pebble stratum, if a hob cutter is used, due to loose soil debris, the hob will be squeezed by the hob. Will produce large deformation, greatly reduce the cutting effect of the hob, and sometimes even lose the cutting ability. Aiming at the characteristics of Beijing's large-size sand and pebble formations, according to the author's construction experience in Japan, it is recommended to use a coiled shell knife, which is arranged on the front face of the disc disk ring and is dedicated to cutting sand pebble. The use of a coiled shell knife can better solve the problem of shield machine cutting soil (sand pebble).
With a large cutter head for cutting the soil in full section, the cutters arranged at different positions on the spokes will gradually decrease from the periphery of the cutter head to the center, and the center point can be regarded as zero in theory. In other words, the movement length of the cut soil in the sealed cabin also gradually decreases from the outside to the inside, and the corresponding soil flow state is getting worse and worse. In addition, a cutter cannot be arranged at the central support part (about 1.5m in diameter). In order to improve the cutting and stirring effect of the soil in the central part, a larger fishtail knife can be designed at the central part.
According to experience, two techniques can be applied to the design and layout of the colored tail knife: one is to let the shield machine cut the soil in two steps. The fish tail knife is used to cut the soil in the center of the small circular section (about 1.5m in diameter), and Expanding to full-section cutting soil, that is, the design of the fishtail knife is not on the same plane as other cutters. Generally, the fishtail knife is advanced by about 600mm to ensure that the fishtail knife cuts the soil first. The second is to design the root of the fishtail knife into Conical, the soil cut by the fishtail when the cutter head rotates. On the basis of tangential and radial movement, a turning motion (like plowing) is added: this can solve the soil in the center part Cutting problems and improve the fluidity of cutting soil, and greatly improve the overall level of shield tunneling.
⑤ Copy knife
The shield machine is generally designed with two copying knives (one spare), which are arranged at both ends of the spokes. During construction, according to the number of over-digging and the requirements of the over-digging range, the profiling knife can be extended and retracted radially from both ends of the spoke to achieve the purpose of imitating cutting. The maximum extension of the profile knife is generally between 80 and 130 mm. When the shield machine is advancing, turning or deflecting in the curved section, the required space is created by copying and cutting the soil to ensure that the shield machine can achieve the curve advancement and smoothness under the conditions of less over-digging and less interference with surrounding soil Turning and deviation correction, so the shield machine needs to be equipped with a profile knife.